Low-pressure roller pump



April 30, 1968 J H, BOERS 3,380,392

LOW-PRESSURE ROLLER PUMP Filed May 12, 1966 INVENTOR. 1w\ 142 dxw 505a?United States Patent 3,380,392 LOW-PRESSURE ROLLER P Jan H. Boers,Owatonna, Minn., assignor to The Owatonna Tool Company, Owatonna, Minn.,a corporation of Minnesota Filed May 12, 1966, Ser. No. 549,506 9Claims. (Cl. 103-136) ABSTRACT OF THE DISCLQSURE A low-pressure rollerpump having a pump body with a cylindrical recess therein and acylindrical rotor member positioned in the recess of the pump body andeccentric therewith for rotation therein. The rotor member has notcheswith roller members therein and the pump body has a pair of passages forintake and exhaust of fluid which extend through the body betweenopposed surfaces thereon and with connecting recesses on the opposedbody surfaces which connect the pair of passages to the cylindricalrecess and the rotor member.

This invention relates to pumps and more particularly to an improvedlow-pressure roller type rotary pump.

In this type of pump, the pump body includes a recess in which a rotoris positioned, the rotor having a plurality of notches with rollermembers therein which are disposed to rotate or roll on the surface ofthe recess in the pump body and cause fluid to be pumped or move aheadof the roller from one port to another. Such a type of pump is wellrecognized and in use.

The present invention is directed to a simplified and improved structurefor such a rotary type pump which substantially reduces the cost of thesame and improves the operation of the pump. The improvement hereinresides in the valving to admit fluid to the rotor member and removefluid therefrom. In the past, pumps of this type have required specialmachining in the pump body to provide the porting from inlet to outletpassages or ports in the pump body. Further, such pumps were limited incapacity in accord with the passages through which fluid is directedfrom the ports to the rotor assembly. In pumps of this type the capacitywas increased by special machining of the valve body to increase thepump area. In the improved design, a single cylindrical recess ispositioned in the pump body with passages or ports located on oppositesides of the recess and removed therefrom to provide for inlet andoutlet of fluid to the pump. The rotor member is also cylindrical withthe plurality of notches about the peripheral edge of the same. Therotor is mounted eccentrically from the geometric center of thecylindrical recess in the pump body. Cylindrical roller memberspositioned in the notches in the rotor member carry the fluid in thepump. These roller members are of a smaller dimension than the notchesto permit movement of the cylindrical roller members therein and additional space for carrying fluid being pumped. Rotation of the rotormember from an external source will cause the cylindrical members in therotor to move under the influence of centrifical force against thesurface of the cylindrical recess and trap fluid to be pumpedtherebetween moving the fluid between inlet and outlet ports. Theimprovement in the present pump is a simplified porting or passage whichmay be utilized at the upper or lower surface of the pump body or onboth surfaces connecting the inlet and outlet passages or ports with thecylindrical recess in which the rotor of the pump is positioned toincrease the capacity for the fluid flowing through the pump and tosimplify machining of the same.

Therefore it is the principal object of this invention to provide animproved rotary pump of the low-pressure roller pump type.

Another object of this invention is to provide in a pump of this type asimplified porting for valving in the pump.

A still further object of this invention is to provide in a pump of thistype an arrangement of valving which eliminates special machining in thevalve body.

A still further object of this invention is to provide an improved pumphaving an increased volumetric output.

Another object of this invention is to provide an improved pump of thistype which is low in cost, simple in design and has a high volumetriccapacity output.

These and other objects of this invention will become apparent from areading of the attached description together with the drawings wherein:

FIGURE 1 is a perspective view of the improved lowpressure roller pump,

FIGURE 2 is a sectional view of the improved roller pump taken along thelines 2-2 in FIGURE 1,

FIGURE 3 is a sectional view of the improved roller pump taken along thelines 3-3 in FIGURE 1,

FIGURE 4 is a top view of the pump body showing an alternate embodimentof the pump porting, and

FIGURE 5 is a sectional view of the pump body taken along the lines 5-5in FIGURE 4.

My improved rotary pump of the low-pressure roller type is shown inperspective in FIGURE 1 in connection with a self-contained portableunit which is adapted to be connected to various types of tools or otherapparatus using fluid under pressure such as to receive such fluidtherefrom and return fluid to the pump. Thus as will be 'seen in FIGURE1, the improved pump indicated generally at 10- incorporates a motorunit 15 connected to the pump unit 18 and mounted on a fluid reservoir20 all connected together and enclosed through a suitable housing orcover. For simplicity, the details of the motor and reservoir togetherwith the connecting housing are omitted. The improved rotary pump willutilize an electric motor which is adapted to be connected to a suitableelectric source and controlled through a suitable control element suchas an electric switch indicated generally at 22. The electric motorprovides a rotary input to the pump which takes fluid, such as hydraulicfluid from a reservoir and directs it to an outlet port such asindicated at 25 to a remote device (not shown) through suitable fluidcouplings (not shown) to supply the remote device with fluid underpressure. A return line (not shown) from the device to the pump unit 10will be connected to a return port 26 in the reservoir and will providefor circulation of the hydraulic fluid to the device to be operated fromthe pump.

For the purposes of the present disclosure, the improved roller typepump is shown herein in connection with a piston type pump indicatedgenerally at 30 which may or may not be incorporated therewith. Theentire piston type pump assembly is enclosed in a casting or body 35having inlet 36 and outlet ports 38 which extend through the body 35 andoperates to take fluid from a reservoir 40 of the reservoir section 20in the housing and direct it through the housing returning the same fromthe body to the outlet passage 38 connected to the outlet port 25. Theaperture or port 26 in the reservoir, as previously indicated, providesthe return passage for fluid directly thereto. In the body 35 thepassage 36 leads directly to the low-pressure roller type rotary pumpand a passage 45 directs the same either through or by passing thepiston type pump 30 to the outlet passage 38.

Motor 15 has an output shaft 50 connected to the low-pressure pump 18and through the low-pressure pump to the piston type pump or highpressure pump 30 and the rotary element thereof. Thus as will be seen inFIG- URE 2, the shaft 50 extends through a body 55 of the low pressurepump which body has a cylindrical recess 60 therein extending throughthe body from an upper surface 61 to a lower surface 62 thereof.Positioned in this cylindrical recess and eccentric thereof is acylindrical type rotor element 70 having a plurality of notches orgrooves 72 about the peripheral surface of the same. In the body 55 ofthe low-pressure pump, the passages 36 and 45 connect to passages 75, 76respectively which passages extend through the pump body between thesurfaces 61, 62. T hese passages are located generally at diametricallyopposed positions in the body 55 on opposite sides of the recess 60 andmay be varied from this diametrical relationship to one which locatesthem generally on opposite sides of the recess depending upon theconfiguration of the body 55 and the location of the passages. Thepassages 75, 76 are connected to the cylindrical recess by a simplifiedporting or grooved recess which extends from the undersurface of thebody 55 to a shallow depth, as indicated at 77, 78 respectively. Suchmachining of the surface of the valve body is readily accessible andeasily accomplished. Thus this surface of the body with this portion ofthe material removed therefrom provides communication of the respectivepassages 75, 76 to the peripheral edge of the cylindrical recessextending over a substantial portion of the surface of the recess onopposite sides of the recess. Thus as will be seen in FIG- URE 2, therecesses 77, 78 extend over approximately 45 angular degrees of thecylindrical recess and connect the passages 75, 76 to the cylindricalrecess 60 on opposite sides of the recess. Rotor 70 is connected to theshaft 50 of the motor 15 and located in the cylindrical recess to beslightly off-center thereof so that one edge of the cylindrical rotorelement 70 will be disposed adjacent and substantially in contact with aportion of the cylindrical surface of the recess 60 while at adiametrically opposed position, a definite gap will exist between theopposite surface of the cylindrical recess and the surface of the rotor.

Positioned in the notches 7 it are a plurality of cylindrical rollermembers 80 which extend in length substantially the thickness of therotor element and are of a diametrical dimension slightly less than thewidth of the notches 72 and the depth of the same. In this type of pump,rotation of the rotor element with the cylindrical roller members 80therein will, through the operation of centrifical force applied to thecylindrical roller members 80, cause the same to be directed against thesurface of the cylindrical recess. Thus the cylindrical roller members89 will slide in the notches 72 against the surface of the cylindricalrecess 69 and roll thereon as the rotor element 70 is rotated throughoperation of the shaft 50. Fluid directed through the passage 36 and thepassage 75 in the pump body 55 will be directed through the groovedrecess 77 and into the spacing between the edge of the rotor element 70and the cylindrical recess 60. The roller members will trap such fluidand cause the fluid to move with the rotor element in the gap betweenthe cylindrical recess and the roller members and within the notches 72to the opposite side of the pump body where the fluid will be dischargedthrough the similar grooved recess 78 and passages 76 and 45 to theoutlet side of the pump. This type of roller pump action is wellrecognized and the oversized notches and grooved recesses or passages onthe surface of the pump body increase the carrying capacity of the pumpand greatly simplify the manufacturing and cost of the same.

An alternate embodiment of the low-pressure pump in FIGURES 4 and showsthe passages 75, 76 through the pump body, indicated at 90, beinglocated on opposite sides of the cylindrical recess 92 in which therotor element is positioned but slightly offset from the diametricallyopposed relationship. In this embodiment, the grooved recesses 94, 95 inthe pump body connect the respective passages 75, 76 to the cylindricalrecess over substantially 135 degrees of the peripheral surface of thecylindrical recess on opposite halves of the recess in the body 90.Further the recesses 94, have corresponding recesses 96, 97 on theopposite surface of the valve body and connecting through the passages75, 76 in the same manner. The rotor configuration for this embodimentis identical with that shown in FIGURE 2 and the cylindrical membersoperate to direct fluid from the passage 75 through the recesses 94, 96around the peripheral surface of the cylindrical recess 9t and to theopposite recesses 95, 97 to the outlet passage 7s. This simplifiedarrangement further increases the fluid carrying capacity in the pumpand greatly simplifies the manufacturing and machining of the same sinceit requires no special passages or ports. In this embodiment, thehousing or lower pump body 35 serves to seal one surface of the rotarypump and an upper seal plate 100 suitably positioned on the uppersurface of the pump body seals the upper side thereof.

For purposes of the present disclosure, a low-pressure pump is shownconnected to a high-pressure pump 30 which is driven from the shaft 50through a shaft extension 102 directly connected thereto and suitablyjournaled through bearing means 104 to drive a wobble plate 106 guidedby suitable bearing plate 108 and operating the second wobble plate 109engaging a plurality of pistons E10, 112 in the high-pressure pump body35. The truncated cylindrical shape of the wobble plate 106 will causethe plate 109 to pivot about a spherical bearing 115 and direct thepistons 110, 112 up and down in the valve body in a conventional lateraltype pumping action. Inlet and outlet control valves for high-pressure,such as is shown at 117 and 120, control fluid flow therethrough. Thepassage 45 of the outlet side of the low-pressure pump extends through atransversely extending passage 130 and through inlet ports 132 to theinlet check valves 117, directing flow into the chambers of the pistons110, 1:12 in the valve body in a conventional manner. The outlet valvescontrol the flow therefrom in accordance with loading of the outlet lineof the pump, as will be hereinafter described. The inlet ports orpassage to the high-pres sure pump includes a bypass valve 142connecting the passage 130 to the port 38 to allow low-pressure fluid toflow directly to the outlet port 25 bypassing the high-pressure pumpupon certain conditions of loading of the pump. Also included in thissection is a bypass valve 145 connecting the outlet passage 45 common tothe inlet port or passage 130 of the low-pressure pump to the reservoir40.

The improved low-pressure roller type rotary pump includes the circularcavity, the notched rotor and the plurality of roller members which aredesigned to fit freely into the notches in the rotor. The bearing forthe rotor of the low-pressure pump is so located that the rotor fitssnugly against one side of the pump cavity leaving a gap on the oppositeside. During operation, the rollers are thrown to the periphery of thecavity by centrifical force thus sealing the adjacent spaces between therollers. In this fashion the roller members trap and transport thehydraulic fluid within the pump. As the rotor revolves, it creates apartial vacuum at the intake port to draw fluid from the reservoir. Atthe opposite side the space between the rotor and the wall of the cavitydecreases and the rollers compress the fluid and discharge it at theoutlet port. The location of the porting and machining of the samegreatly reduces tolerances and cost of the pump.

In the operation of the pump with no loading or with light loading onthe outlet line, for example 200 p.s.i., fluid is channeled directlyfrom the outlet of the lowpres'sure pump through the bypass valve 142 toprovide the high volume delivery. The low-pressure fluid is alsodelivered to the high-pressure pump to keep the pistons seated againstthe wobble plate. During high-pressure delivery, the low-pre'ssure pumpcontinues to function as it did down the low-pressure cycle but with asystem loaded at a pressure higher than that for which the low-pressurepump is designed, for example 200 p.'s.i., a build up in pressure in theline forces the bypass valve 145 to open so that a portion of thelow-pressure fluid is returned to the reservoir 40. As the line pressurecontinues to increase it closes the bypass valve v142 and enoughlow-pressure fluid flow is maintained to satisfy the low volumerequirements of the high-pressure pump. The low-pressure fluid is forcedthrough the intake valves of the high-pressure cylinder and iscompressed by the pistons to line pressure. This pressure isconsiderably higher than the output of the low-pressure pump, forexample up to 10,000 11.8.1. The actual line pressure depends upon theloading of the outlet or system to which the pump is connected. In theevent that system loading exceeds a predetermined maximum, suitablerelief valving (not shown) is normally included in the line or may beincluded in the pump to prevent damage to the equipment. Thus theimproved pump may be utilized for high and low-pressure operationalthough the high pressure side is a conventional pump unit and itsdetails may vary.

The improved low-pressure roller type rotary pump incorporates asimplified pump body with a rotor and roller configuration mounted in acylindrical recess in the pump body which permits movement of fluidthrough the pump body from the inlet to outlet passages therein. Theconnecting of the inlet and outlet passages to the inlet and outletports and in communication .with the rollers eliminates the necessity ofspecial machining in that the grooved recesses are positioned on theexposed surfaces of the pump body 55 and directly connect thecylindrical recess in the pump body with the passages 75, 76 therein.This greatly reduces the cost of the unit and increases the chiciency ofoperation of the same by substantially increasing the fluid flowcharacteristics of the low-pressure pump.

In considering this invention it should be remembered that the presentdisclosure is intended to be illustratively only and the scope of theinvention should be determined by the appended claims.

What is claimed is:

1. A rotary pump comprising, a pump body having a cylindrical recesstherein extending between two axially opposite surfaces of the body, apair of passages in said body extending to one of the axially oppositesurfaces of the body and being located outside of the cylindricalrecess, a pair of grooved recesses positioned in the pump body eachextending from said one surface thereof a given depth toward said otheraxially opposite surface and connecting a portion of the cylindricalrecess respectively with one of said passages to define flow passagesinto and out of a working chamber of the pump, a cylindrical rotormember positioned in said cylindrical recess of said body and eccentrictherewith, said rotor member having a thickness dimension such thataxially opposite surfaces thereof extend to the axially oppositesurfaces of the pump body and with a plurality of notches extendingtherethrough at the peripheral edge of the same, a plurality ofcylindrical roller members positioned respectively in said notches andfreely movable therein and having a length dimension such as to extendbetween the axially opposite surfaces of the rotor member, meansconnected to said rotor member to rotate the same in said cylindricalrecess to cause said roller members in said notches to engage and rollon the inner surface of said cylindrical recess being adapted to causefluid from one of said passages to move through the flow passage definedby the grooved recess in communication therewith and ahead of saidroller member between the surface of said cylindrical recess and theperipheral surface of said rotor member to the other of the flowpassages defined by said other grooved recess and the other of saidpassages, and means enclosing the body and the rotor member at saidaxially opposite surfaces and cooperating with the grooved recesses inthe pump body to define said flow passages to and from the workingchamber of said pump.

2. The rotary pump of claim 1 in which the pair of passages are inletand outlet passages in said body which are located therein onsubstantially opposite sides of said cylindrical recess.

3. The rotary pump of claim 2 in which each of said grooved recessesabut over at least one-quarter of the peripheral surface of saidcylindrical recess of said body on at least one surface thereof.

4. The rotary pump of claim 3 in which the pair of passages are inletand outlet passages in said body which are located therein ondiametrically opposite sides of said cylindrical recess.

5. The rotary pump of claim 3 in which the grooved recesses arepositioned on each of the opposite surfaces of said body and on oppositesides of said cylindrical recess to connect said two passages at saidopposite surfaces of said body and on opposite surfaces of said body.

6. The rotary pump of claim 5 in which each of the grooved recesses insaid body extend over approximately 37 /z% of the peripheral surface ofsaid cylindrical recess.

7. The rotary pump of claim 6 in which the notches in the rotor membersare substantially rectangular in cross section and equally spaced aboutthe peripheral edge of the same.

8. The rotary pump of claim 7 in which the notches in said rotor memberhave dimensions which are greater than the diametrical dimension of saidcylindrical roller members such that fluid may flow around said rollermembers in said notch and be carried with the rotor member between saidpassages.

9. The rotary pump of claim 8 in which the opposite surfaces of the bodymember and the rotor member are disposed at substantially coincidingplanes.

References Cited UNITED STATES PATENTS 1,762,418 1/1930 Petersen 1031362,588,342 3/1952 Bidwell 103-136 2,635,550 4/1953 Granberg 103-1363,211,104 10/1965 Rosaen 103136 3,247,803 4/1966 Halsey 103-136 FRED C.MATTERN, JR., Primary Examiner. WILLIAM L. FREEH, Examiner.

